The present invention relates to a process and a device for the production of foam slabs of angular cross-section in a flock composite, foam flocks being introduced into a molding box with adjoining mold walls and the filling then being compacted to the desired density or slab height by means of a stamp and the finished slab subsequently being removed from the mold.
The production of composite slabs of angular cross-section from foam flocks, for example polyurethane foam is generally known. The flocks are sprayed with a binder or sintered or fused with one another. Depending-on the nature of the filling cross-section of the chosen molding box, the finished slabs, as a rule have a rectangular or square cross-section but they can also have angular or circular form.
While a density distribution which is homogeneous over the filling cross-section can be achieved in circular slabs, it is a disadvantage in the case of angular filling cross-sections that, in slab production, in particular as a function of the flock size and of the tendency of the flocks to form bridges, hollow spaces and rounded edges are formed during introduction of the flocks into the molding box, especially, in the corners thereof; a lower density, furthermore, forming in these corners rather than in the inside of the slab. In particular, the processing of flocks of the usual sizes of 12 to 15 mm present such difficulties.
Because of the hollow spaces and rounded-off corners and the inhomogeneous densityxe2x80x94taken over the slab cross-sectionxe2x80x94attempts have already been made to subsequently stuff flocks into the corners manually. This means a higher expenditure of time during production, and the density achieved in the corners in such a manner depends solely on the skill of the operating staff and is not reproducible.
Therefore, for use of the slab material for objects with greater requirements, it is therefore often necessary to cut the finished angular flock composite slab to eliminate untrue edges and inhomogeneous corners. Needless to say, about 10% waste results from this practice, for which production work is lost, even though this waste as a rule can be recycled for lesser quality processes.
Therefore, an object of the present invention is to produce angular foam composite slabs with sharp edges and with a homogeneous density distribution over the entire slab cross-section by compacting the flock material.
This object is achieved in that before the foam flocks are introduced, the cross-section in every corner formed by two mold walls are extended to a filling cross-section, and after the foam flocks have been introduced, the filling cross-section is reduced to the desired shape of the cross-section of the slab to be produced, and only then, is the filling compacted to the desired density or slab height.
As a result of this measure, the total finished flock composite slab can be used, even for increased quality requirements, in particular, because of its homogeneous density distribution and fully filled corners. As a result, there is no waste. Subsequent manual stuffing is also not necessary. It goes without saying that the extension and reduction of the filling cross-section must take place over the entire height of the molding box or the filling height.
In practice, usually rectangular, in particular, square slabs are produced. However, the new invention can be applied to the production of all angular slabs. The more corners the slab has, the lower is the risk of inhomogeneity of density and unfilled corners during its conventional production. On the other hand, use of the new process is particularly advantageous for production of four-cornered or even only three-cornered slabs.